There is a nice long list of over 100 answers to the question of why software estimates are off at Quora: http://www.quora.com/Engineering-Management/Why-are-s

There is a nice long list of over 100 answers to the question of why software estimates are off at Quora: http://www.quora.com/Engineering-Management/Why-are-software-development-task-estimations-regularly-off-by-a-factor-of-2-3?share=1 http://www.quora.com/Engineering-Management/Why-are-software...